Thrust controlling apparatus

ABSTRACT

Apparatus comprises elongate shroud surrounding jet engine. Aft portion of shroud extends rearwardly beyond stream. Passages through shroud wall aft of nozzle exit admit ambient air to define shroud aft portion as an ejector ring. A blocker door is provided for each passage and swings on lateral pivot from first forward position blocking forward portion of its passage, through intermediate positions partially blocking rearward flow of exhaust stream and redirecting portion of stream out through passages, to second full aft position where doors meet to block all rearward flow and redirect it out through passages. For supersonic flight afterburner operation, doors are bodily moved to fully block passages. Apparatus may be used with conventional jet or fan jet engines. Doors may be operated independently to modify the direction of the thrust vector.

United States Patent Murday 1 Mar. 7, 1972 Inventor:

Assignee:

Filed:

Appl. No.:

US. Cl ..239/265.29, 239/265. 17, 239/265.39 Int. Cl. .Q .3640 15/06Field of Search ..239/265.25, 265.27. 265.29,

References Cited UNITED STATES PATENTS FOREIGN PATENTS OR APPLICATIONS1,100,385 2/1961 Germany ..239/265.25

OTHER PUBLICATIONS lnteravia, The Viggen Thrust Reverser System, March,1969, pp. 276- 277.

Primary Examiner-M. Henson Wood, Jr.

Assistant ExaminerReinhold W. Thieme Attorney-George E. Pearson 5 7]ABSTRACT Apparatus comprises elongate shroud surrounding jet engine. Aftportion of shroud extends rcarwardly beyond stream. Passages throughshroud wall aft of nozzle exit admit ambient air to define shroud aftportion as an ejector ring. A blocker door is provided for each passageand swings on lateral pivot from first forward position blocking forwardportion of its passage, through intermediate positions partiallyblocking rearward flow of exhaust stream and redirecting portion ofstream out through passages, to second full aft position where doorsmeet to block all rearward flow and redirect it out through passages.For supersonic flight afterbumer operation, doors are bodily moved tofully block passages. Apparatus may be used with conventional jet or fanjet engines. Doors may be operated independently to modify the directionof the thrust vector.

12 Claims, 8 Drawing Figures PATENTEDMAR" 7 I972 sum 1 0F 2 INVENTOR.DAVID A. MURDAY ATTORNEY PATENTEDMAR 71972 3,647, 141

SHEET 2 BF 2 INVENTOR. DAVID A. MURDAY Mam ATTORNEY TIIRUST CONTROLLINGAPPARATUS BACKGROUND OF THE INVENTION I This invention lies in the fieldof gas turbine engines, commonly called jet engines, which producereaction thrust by ejecting a high velocity stream of gas from theexhaust nozzle or tail pipe of the gas turbine. Airplanes equipped withjet engines have two problems on which a great deal of effort has beenexpended. One of these is that the exhaust gas stream creates a veryhigh level of sound energy or noise in a wide range of frequencies and aportion of this noise reaches the ground at an energy level which is notacceptable to the public. The other problem is that jet airplanes havevery highlanding speeds which place an excessive burden on the wheelbrakes unless some retarding means is provided to assist indeceleration. In addition, the operation of military airplanes in steepdives or carrier landing approaches requires a high degree of speedbraking in flight frequently followed by a need for immediate full poweroperation.

The invention is directed to apparatus which reduces the base drag andsound level by mixing free stream air with the gasstream and apparatuswhich reverses the direction of exhaust gas flow to produce counterthrust, and is more particularly directed to combined apparatus whichperforms both of these functions.

SUMMARY OF THE INVENTION The present invention provides a verysatisfactory solution to the general problem and offers a combinationapparatus in which an injector ring induces the free airstream into amixing zone with the exhaust gas stream and the injection inlet passagesalso serve as outlet passages for reverse thrust flow. A plurality ofblocker doors cooperate with the passages to guide the inflow and aremovable to positions to force the exhaust stream outwardly through thepassages. There is a minimum total amount of apparatus and the actuatingmechanism is very simple. The net result is minimum weight and maximumreliability compared to a translating sleeve-type reverser.

Generally stated, in generic form, the apparatus comprises an elongatestreamlined shroud connected to and surrounding the engine and may bethe airframe, nacelle or other portion of the airplane structure. Theaft portion of the shroud extends rearwardly beyond the exit end of thenozzle to surround and control the exhaust gas stream. A plurality ofairflow passages (three being best suited to a single-engine airplane)spaced around the periphery of the shroud aft of the exit end of thenozzle extend through the shroud wall from the exterior to the interior,avoiding the horizontal and vertical flight control surfaces, and theaxes of the flow paths converge rearwardly for efficient flow andmixing. Their form also acts to direct the exhaust gas stream outwardlyand forwardly to produce reverse thrust. Thus the aft portion of theshroud constitutes a dual purpose fixed ejector ring.

A blocker door is provided for each passage and is mounted on pivotmeans carried by the fixed ejector ring for swinging fore-and-aft aboutlateral axes. In their first, extreme forward position the doors blockthe forward portions of the passages and form part of the forward wallto guide the airflow inwardly around the turbine jet stream. They may beadjusted to various intermediate positions in which their trailing edgesproject inwardly toward the shroud axis, partially blocking the rearwardflow of the exhaust stream and forcing portions of the stream outwardlythrough the passages to produce any desired degree of reverse thrustwhich is particularly valuable for military maneuvers. When the doorsare swung to their second, extreme aft position, they meet at the axisof the shroud and completely block rearward flow through the ejectorring, redirecting the flow laterally outward and forward through thepassages to produce reverse thrust.

In a modification, the doors are pivotally mounted on the free ends ofpivoted arms which may be swung outward to bodily move the doors topositions in which they completely block the passages. This modificationis used for afterburner operation when no ejector air is desired and thefull area of the ejector ring is needed for the jet stream.

The apparatus is equally well suited for use with conventional jet orfan jet engines. The doors are normally operated in unison but they maybe operated independently to modify the direction of the thrust vectorand thus induce a pitching and/or yawing motion to the airplane.

BRIEF DESCRIPTION OF THE DRAWINGS Various other advantages and featuresof novelty will become apparent as the description proceeds inconjunction with the accompanying drawings, in which:

FIG. 1 is a schematic side view in section of a jet engine within ashroud incorporating the invention;

FIG. 2 is a schematic side view in section of part of the ejector ringportion of the shroud showing a blocker door in its first, extremeforward position;

FIG. 3 is a view similar to FIG. 2 with the blocker door in intermediateposition;

FIG. 4 is a view generally similar to FIG. 2, but showing the blockerdoor in its extreme aft, thrust reversing position;

FIG. 5 is a view generally similar to FIG. 2, but showing a modifiedmounting arrangement for the blocker door;

FIG. 6 is a view generally similar to FIG. 5, but showing the blockerdoor moved radially outwardly from the shroud axis to a positioncompletely closing the air inlet passage;

FIG. 7 is a view of the modified structure of FIGS. 5 and 6 with theblocker door swung to full-thrust reversing position;

FIG. 8 is a sectional view taken along the line 8-8 of FIG. 1, thetrailing edges of the blocker doors being shown in broken lines with thedoors swung to their positions of FIG. 3 and FIG. 4, respectively.

DESCRIPTION OF PREFERRED EMBODIMENTS The general arrangement illustratedin FIG. 1 shows one preferred form of the invention embodied in theshroud 22 of a typical jet engine installation. A conventional turbojetengine shaft, not shown, has mounted on its forward end to a usual axialflow compressor, also not shown, and is provided at its aft end with atail pipe or nozzle 20 for ejecting the jet stream of exhaust gases. Theshroud 22 is provided to surround the components of the engine, and maybe a portion of afuselage or wing or other aircraft structure, but forsimplicity is shown as having the form of a typical jet engine nacelle,which is generally annular in cross section and coaxial with the engine.The forward portion of the shroud extends forward to define between theshroud and nozzle 20 a passage 24 which may convey fan air or merelyprovide for static air insulation around the turbine and nozzle. Thus,the installation is a conventional turbojet engine type but is equallywell adapted for use with a fan-type engine.

The aft portion 28 of the shroud extends rearwardly beyond the exit end30 of the nozzle to define a mixing zone 32 for mixing turbine air withfan air, turbine air with cooling air, turbine air with atmospheric airinduced through passages 34, or any combination of the aforesaidmixtures. A plurality of passages 34, preferably three, are formedthrough the wall of the shroud aft of the lateral plane of the exit end30 of the nozzle and they are preferably equally spaced around theperiphery to balance the thrust vector. They extend fully through thewall from the exterior to the interior and are angled inwardly andrearwardly to induce free stream air into the mixing zone 32 where itmixes with the air, if any, from passage 24 and the exhaust gas streamfrom nozzle 20. Thus, portion 28 of the shroud is an ejector ring. Ablocker door 36 is provided for each passage 34 and is pivotally mountedat 38 for swinging about a lateral axis substantially perpendicular tothe longitudinal axis of the shroud to modify air and gas flow in themanner hereafter described.

The schematic illustration in FIG. 2 shows the lower rear portion of theshroud in greater detail than in FIG. 1 with a portion of the nozzle 20.FIG. 8, taken on line 8-8 of FIG. 1, shows the peripheral spacing of thepassages and illustrates the action of the blocker doors. In FIG. 2, itwill be seen that each door is generally airfoil shaped in fore-and-aftsection and is arcuate in cross section so that its inner wall 40 formsa part of the contour of the inner wall 42 of the ejector ring 28.

In the first, extreme forward position of FIG. 2 the thick leading edge44 of the door, the surface of which is preferably arcuate about pivot38, contacts wall portion 46 of the passage in sealing relation. Thusthe door blocks the forward portion of the passage. The upper rearsurface 48 of the door cooperates with surfaces 50 and 52 of the passageto define an inwardly and rearwardly angled flow path for the freestream air to enter mixing zone 32 where it is mixed with the hot enginegases before leaving the ejector ring. Since the free stream air iscooler, the gaseous mixture is greatly cooled with reduced noise level.In addition, the tube of cooler air surrounding the hot gases furtherreduces the noise level on emission to free air.

Turning to FIG. 8, it will be seen that each door is mounted on itspivot'members 38 in the parallel sidewalls 54 of its respective passage34. At least one of the pivot members for each door is provided with alever arm 56 which, as seen in FIG. 2, is connected pivotally to apiston rod 58 slidably extending from the cylinder 60 of a servomotor,the cylinder being pivotally mounted to the shroud structure at 62.Operation of the servomotor in known manner will move the blocker doorthrough intermediate positions, one of which is shown in FIG. 3, to thesecond, extreme aft position shown in FIG. 4. The trailing edge 64 ofeach door tapers rearwardly from the full width of the door to a point,so that the trailing edge margins of the doors may engage in sealingrelation for full blocking of the rearward flow of the gas stream onoccasion.

It is desired particularly in certain military maneuvers to be able toapply a high level of reverse thrust while maintaining engine operationat substantially full power. One example is a steep dive where thevertical velocity must not be excessive and yet full power must bealmost instantly available for full thrust. Another example is a carrierlanding where forward speed is greatly reduced but full thrust must bealmost instantly available in case of a waveoff. For this purpose, thedoors may be moved to a selected intermediate position, such as shown inFIG. 3. In this position, leading edge 44 of the door is in contact withsurface 52, blocking ingress of free stream air to the mixing zone andproviding a wide open flow path for outflow of exhaust gas and fan air,if present, to produce a high level of reverse thrust. As will be seenin FIG. 8, the trailing edges 64 of the doors are now in the broken linepositions 66, leaving a Y-shaped passage for a portion of the jetoutflow. With this adjustment the engine may be operated at a very highrotational speed and power level with no increase in back pressure whilehigh level reverse thrust is being produced. When full thrust isdemanded, the doors are returned to their first position without movingthe throttle. Full thrust is achieved immediately.

When full reverse thrust is required, as for landing runs, the doors areswung to their second, extreme aft position shown in FIG. 4. Thetrailing edges of the doors engage along broken lines 68 to completelyblock rearward flow of the exhaust stream. As seen in FIG. 4, the doorsnow form a forwardly converging cone which provides a more effectiveflow coefficient in redirecting the flow of the gas stream.

The modification of FIG. is generally similar to the showing of FIG. 2.However, in this modification an arm 70 is provided having its aft endpivotally mounted at 72, one one each side of each blocker door openingin the shroud 22a. A servomotor for actuating at least one of each pairof the arms 70 comprises a cylinder 74 pivotally connected at 76 to theshroud 22a, and a piston rod 78 pivotally connected at 80 to the arm 70.A blocker door 360 is pivotally mounted at 82 between the free ends ofeach pair of arms 70.

In FIG. 5, the door 36a is shown in substantially the same air ingestingposition as that shown for the corresponding door 36 in FIG. 2.

When the engine of the embodiment shown in FIGS. 5 7 is to be operatedin afterburning condition, the exhaust nozzle 20 is extended in a usualmanner from its normal, broken line position 84 in FIG. 6, to its solidline position in that figure. Also, in order to seal off the air inletpassages 34a, and to provide maximum volume for the exhaust gases, thedoors 36a are swung rearwardly slightly from their positions in FIG. 5and the arms 70 are swung outwardly to their positions shown in FIG. 6,thereby moving the blocker doors 36a radially outwardly to close off theair inlet passages 34a.

The servomotors for swinging the doors 36a about their respective pivots82 each comprises a piston rod 58a and cylinder 60a, and, when the arms70 are swung to their axially inward position relative to the shroud22a, are operated in the same manner as the cylinder 60 and piston rod58 shown in FIGS. ll 4 and 8.

FIG. 7 shows the door 36a in its full blocking or thrust reversingposition, which corresponds to the showing in FIG.

The servomotors for actuating the blocker doors are normally operated inunison as described previously herein. However, they may also beactuated individually if desired to modify the direction of the thrustvector for inducing a pitch or yaw effect. The control and power supplymeans are not shown in detail since they are matters of design withinthe state of the art.

It will be apparent that the invention disclosed herein providesapparatus which provides thrust reversal which may be modulated to anydesired degree with a minimum of weight and complication because of thedual functioning of most of its components, and in addition decreasesthe sound level of jet engine noise and reduces its own increase in basedrag through induced tertiary air.

What is claimed as new and useful and desired to be secured by USLetters Patent is:

l. Thrust controlling apparatus for use in combination with a jet enginehaving a rearwardly discharging nozzle and adapted to produce reactionthrust, comprising: an elongate shroud of generally annular crosssection connected to and surrounding said engine, the aft portion ofsaid shroud extending rearwardly beyond the exit end of said nowe tosurround and control the exhaust gas stream issuing therefrom; aplurality of peripherally spaced passages extending through the wall ofsaid aft portion from the exterior to the interior thereof and aft ofthe plane of the exit end of said nozzle for inflow of ambient air tomix with the exhaust gas stream and make said aft portion an ejectorring; and a blocker door for each passage pivotally mounted to theejector ring for fore-and-aft swinging about an axis perpendicular tothelongitudinal axis of the shroud; said doors each being pivotallymovable between a first extreme forward position blocking the forwardportion of its respective passage and directing ambient airflow inwardlyand rearwardly through the aft portion of said passages, throughintermediate positions partially blocking rearward flow of the exhauststream and redirecting a portion of it laterally outward through saidpassages to a second extreme rearward position cooperating with eachother to substantially completely block rearward flow of the exhauststream and redirect it laterally outward through said passages withincreased effective flow coefficient.

2. Apparatus as claimed in claim 1; the .wall of said shroud beingspaced radially outward from the wall of the nozzle to define a path forair to flow rearwardly into the mixing zone defined by said ejectorring.

3. Apparatus as claimed in claim 1 each door having an airfoil shape infore-and-aft section and arcuate in cross section; the thickened leadingedge portion contacting the forward wall of the passage when the door isin its first position and the inner surface of the door being shaped todefine a portion of the contour of the inner wall of the ejector ring.

4. Apparatus as claimed in claim 3; the thickened leading edge portioncontacting the rear wall of the passage in at least one intermediateposition to block inflow of ambient air to the interior of the ejectorring.

5. Apparatus as claimed in claim 1; the number of passages and doorsbeing at least three; the trailing edge of each door tapering rearwardfrom the full width of the door to a point; the included angle beingchosen to cause the trailing edges to engage in substantially completesealing relation in the second full blocking position.

6. Apparatus as claimed in claim 5; the pivotal mountings of the doorsbeing so located that in the full blocking position the inner surfacesof the doors form a forwardly convex cone to initially guide the exhauststream into a reverse flow path and hence prevent back pressuring theengine.

7. Apparatus as claimed in claim 1; the flow path axis of each passagebeing angled inwardly and rearwardly for efficient ejector inflow andfor directing reverse thrust gas flow laterally outward and forward.

8. Apparatus as claimed in claim 1; said doors being operableindependently of each other each about a separate and distinct pivotaxis to modify the direction of the thrust vector.

9. Apparatus as claimed in claim 1; each door being movable generallyradially outward to a position totally blocking its respective passageto prevent flow therethrough in either direction during afterburneroperation of the engine.

10. Apparatus as claimed in claim 9; including generally fore-and-aftextending supporting arms for each door; said arms being pivotallymounted at their aft ends to the ejector ring for swinging about lateralaxes; said doors being pivotally mounted to the fore ends of said armsfor swinging about lateral axes; and the fore ends of said arms beingswingable away from the axis of the shroud to carry said doors intototal passage blocking positions.

11. Thrust controlling and ejector mechanism for use in combination witha jet engine having an exhaust nozzle for discharging rearwardly anexhaust gas stream adapted to produce reaction thrust, said mechanismcomprising: a shroud of generally annular cross section surrounding saidengine, said shroud extending rearwardly beyond the exit end of thenozzle to surround such exhaust gas stream, a plurality ofcircumferentially spaced door mounting injector passages ex tendingthrough the wall of said shroud and terminating aft of said nozzle, anda blocker door mounted in each door passage to swing bodily about anaxis perpendicular to the shroud axis and offset inwardly of the shroudfrom its respective door for fore-and-aft swinging movement of each doorabout its axis between an extreme forwardly swung position wherein itblocks the forward portion of its respective passage with its axiallyoutward surface sloping rearwardly and inwardly to direct ambientairflow inwardly and rearwardly through said passages, an intermediate,partially rearwardly swung position wherein it opens its respectivepassage ahead of the door thereby partially blocking rearward flow ofsuch exhaust gas stream through the shroud and directs a portion of suchstream radially outwardly through said passages ahead of the doors forpartial thrust reversal effect, and an extreme, rearwardly swungposition, thereby retaining open the passages ahead of the doors,blocking rearward flow of such exhaust stream, and directing such streamlaterally outward through said passages with a forward component formaximum thrust reversal effect.

12. Thrust controlling and ejector mechanism as defined in claim 11wherein the axis about which each door swings is movable toward and awayfrom the shroud axis for movement of the doors outwardly to passageclosing condition in an intermediately swung position about theirrespective axes.

1. Thrust controlling apparatus for use in combination with a jet enginehaving a rearwardly discharging nozzle and adapted to produce reactionthrust, comprising: an elongate shroud of generally annular crosssection connected to and surrounding said engine, the aft portion ofsaid shroud extending rearwardly beyond the exit end of said nozzle tosurround and control the exhaust gas stream issuing therefrom; aplurality of peripherally spaced passages extending through the wall ofsaid aft portion from the exterior to the interior thereof and aft ofthe plane of the exit end of said nozzle for inflow of ambient air tomix with the exhaust gas stream and make said aft portion an ejectorring; and a blocker door for each passage pivotally mounted to theejector ring for fore-and-aft swinging about an axis perpendicular tothe longitudinal axis of the shroud; said doors each being pivotallymovable between a first extreme forward position blocking the forwardportion of its respective passage and directing ambient airflow inwardlyand rearwardly through the aft portion of said passages, throughintermediate positions partially blocking rearward flow of the exhauststream and redirecting a portion of it laterally outward through saidpassages to a second extreme rearward position cooperating with eachother to substantially completely block rearward flow of the exhauststream and redirect it laterally outward through said passages withincreased effective flow coefficient.
 2. Apparatus as claimed in claim1; the wall of said shroud being spaced radially outward from the wallof the nozzle to define a path for air to flow rearwardly into themixing zone defined by said ejector ring.
 3. Apparatus as claimed inclaim 1 each door having an airfoil shape in fore-and-aft section andarcuate in cross section; the thickened leading edge portion contactingthe forward wall of the passage when the door is in its first positionand the inner surface of the door being shaped to define a portion ofthe contour of the inner wall of the ejector ring.
 4. Apparatus asclaimed in claim 3; the thickened leading edge portion contacting therear wall of the passage in at least one intermediate position to blockinflow of ambient air to the interior of the ejector ring.
 5. Apparatusas claimed in claim 1; the number of passages and doors being at leastthree; the trailing edge of each door tapering rearward from the fullwidth of the door to a point; the included angle being chosen to causethe trailing edges to engage in substantially complete sealing relationin the second full blocking position.
 6. Apparatus as claimed in claim5; the pivotal mountings of the doors being so located that in the fullblocking position the inner surfaces of the doors form a forwardlyconvex cone to initially guide the exhaust stream into a reverse flowpath and hence prevent back pressuring the engine.
 7. Apparatus asclaimed in claim 1; the flow path axis of each passage being angledinwardly and rearwardly for efficient ejector inflow and for directingreverse thrust gas flow laterally outward and forward.
 8. Apparatus asclaimed in claim 1; said doors being operable independently of eachother each about a separate and distinct pivot axis to modify thedirection of the thrust vector.
 9. Apparatus as claimed in claim 1; eachdoor being movable generally radially outward to a position totallyblocking its respective passage to prevent flow therethrough in eitherdirection during afterburner operation of the engine.
 10. Apparatus asclaimed in claim 9; including generally fore-and-aft extendingsupporting arms for each door; said arms being pivotally mounted attheir aft ends to the ejector ring for swinging about lateral axes; saiddoors being pivotally mounted to the fore ends of said arms for swingingabout lateral axes; and the fore ends of said arms being swingable awayfrom the axis of the shroud to carry said doors into total passageblocking positions.
 11. Thrust controlling and ejector mechanism for usein combination with a jet engine having an exhaust nozzle fordischarging rearwardly an exhaust gas stream adapted to produce reactionthrust, said mechanism comprising: a shroud of generally annular crosssection surrounding said engine, said shroud extending rearwardly beyondthe exit end of the nozzle to surround such exhaust gas stream, aplurality of circumferentially spaced door mounting injector passagesextending through the wall of said shroud and terminating aft of saidnozzle, and a blocker door mounted in each door passage to swing bodilyabout an axis perpendicular to the shroud axis and offset inwardly ofthe shroud from its respective door for fore-and-aft swinging movementof each door about its axis between an extreme forwardly swung positionwherein it blocks the forward portion of its respective passage with itsaxially outward surface sloping rearwardly and inwardly to directambient airflow inwardly and rearwardly through said passages, anintermediate, partially rearwardly swung position wherein it opens itsrespective passage ahead of the door thereby partially blocking rearwardflow of such exhaust gas stream through the shroud and directs a portionof such stream radially outwardly through said passages ahead of thedoors for partial thrust reversal effect, and an extreme, rearwardlyswung position, thereby retaining open the passages ahead of the doors,blocking rearward flow of such exhaust stream, and directing such streamlaterally outward through said passages with a forward component formaximum thrust reversal effect.
 12. Thrust controlling and ejectormechanism as defined in claim 11 wherein the axis about which each doorswings is movable toward and away from the shroud axis for movement ofthe doors outwardly to passage closing condition in an intermediatelyswung position about their respective axes.